The invention concerns a device for a pump and more particularly a construction of a shaft for a mixing means corotating with the pump impeller.
When pumping liquids containing larger amounts of pollutants, certain problems arise. The pump impeller must be so designed that the pollutants do not clog the impeller and in addition the impeller as well as the surrounding housing must be manufactured of a material that can stand wear. This is especially important when pumping in mines where the water contains large amounts of wearing particles.
When pumping in mines it also often occurs that the pollutants have settled and form a layer of a relatively solid consistence at the bottom. This layer is not possible to pump with conventional means, but must be transformed into a solution in one way or another. This may for instance be achieved by help of some sort of mixer.
In order to eliminate the need for a separate mixer, there exist solutions where a pump is provided with an integrated mixer which extends beyond the pump impeller and on the same shaft. The intention is that the mixer shall stir the layer and cause it to mix with the liquid above and thus make it possible to pump.
Such a device has a good function as long as the sediment is not too solid or non-uniform. If this is the fact, the mixer shaft will be deflected when it hits harder material or lumps. If such deflections become too large, the shaft and its bearing might become damaged and cause expensive repairs.
The purpose of this invention is to diminish the risks for damage that make repairs difficult. The characteristics are stated in the claims.